package com.zjxfood.view;

import java.util.LinkedList;
import java.util.Queue;

import android.content.Context;
import android.database.DataSetObserver;
import android.graphics.Rect;
import android.util.AttributeSet;
import android.view.GestureDetector;
import android.view.GestureDetector.OnGestureListener;
import android.view.MotionEvent;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ListAdapter;
import android.widget.Scroller;

public class HorizontalListView extends AdapterView<ListAdapter>{
	 public boolean mAlwaysOverrideTouch = true;  
	    protected ListAdapter mAdapter;  
	    private int mLeftViewIndex = -1;  
	    private int mRightViewIndex = 0;  
	    protected int mCurrentX;  
	    protected int mNextX;  
	    private int mMaxX = Integer.MAX_VALUE;  
	    private int mDisplayOffset = 0;  
	    protected Scroller mScroller;  
	    private GestureDetector mGesture;  
	    private Queue<View> mRemovedViewQueue = new LinkedList<View>();  
	    private OnItemSelectedListener mOnItemSelected;  
	    private OnItemClickListener mOnItemClicked;  
	    private OnItemLongClickListener mOnItemLongClicked;  
	    private boolean mDataChanged = false;  
	      
	  
	    public HorizontalListView(Context context, AttributeSet attrs) {  
	        super(context, attrs);  
	        initView();  
	    }  
	      
	    private synchronized void initView() {  
	        mLeftViewIndex = -1;  
	        mRightViewIndex = 0;  
	        mDisplayOffset = 0;  
	        mCurrentX = 0;  
	        mNextX = 0;  
	        mMaxX = Integer.MAX_VALUE;  
	        mScroller = new Scroller(getContext());  
	        mGesture = new GestureDetector(getContext(), mOnGesture);  
	    }  
	      
	    @Override  
	    public void setOnItemSelectedListener(AdapterView.OnItemSelectedListener listener) {  
	        mOnItemSelected = listener;  
	    }  
	      
	    @Override  
	    public void setOnItemClickListener(AdapterView.OnItemClickListener listener){  
	        mOnItemClicked = listener;  
	    }  
	      
	    @Override  
	    public void setOnItemLongClickListener(AdapterView.OnItemLongClickListener listener) {  
	        mOnItemLongClicked = listener;  
	    }  
	  
	    private DataSetObserver mDataObserver = new DataSetObserver() {  
	  
	        @Override  
	        public void onChanged() {  
	            synchronized(HorizontalListView.this){  
	                mDataChanged = true;  
	            }  
	            invalidate();  
	            requestLayout();  
	        }  
	  
	        @Override  
	        public void onInvalidated() {  
	            reset();  
	            invalidate();  
	            requestLayout();  
	        }  
	          
	    };  
	  
	    @Override  
	    public ListAdapter getAdapter() {  
	        return mAdapter;  
	    }  
	  
	    @Override  
	    public View getSelectedView() {  
	        //TODO: implement  
	        return null;  
	    }  
	  
	    @Override  
	    public void setAdapter(ListAdapter adapter) {  
	        if(mAdapter != null) {  
	            mAdapter.unregisterDataSetObserver(mDataObserver);  
	        }  
	        mAdapter = adapter;  
	        mAdapter.registerDataSetObserver(mDataObserver);  
	        reset();  
	    }  
	      
	    private synchronized void reset(){  
	        initView();  
	        removeAllViewsInLayout();  
	        requestLayout();  
	    }  
	  
	    @Override  
	    public void setSelection(int position) {  
	        //TODO: implement  
	    }  
	      
	    private void addAndMeasureChild(final View child, int viewPos) {  
	        LayoutParams params = child.getLayoutParams();  
	        if(params == null) {  
	            params = new LayoutParams(LayoutParams.FILL_PARENT, LayoutParams.FILL_PARENT);  
	        }  
	  
	        addViewInLayout(child, viewPos, params, true);  
	        child.measure(MeasureSpec.makeMeasureSpec(getWidth(), MeasureSpec.AT_MOST),  
	                MeasureSpec.makeMeasureSpec(getHeight(), MeasureSpec.AT_MOST));  
	    }  
	      
	      
	  
	    @Override  
	    protected synchronized void onLayout(boolean changed, int left, int top, int right, int bottom) {  
	        super.onLayout(changed, left, top, right, bottom);  
	  
	        if(mAdapter == null){  
	            return;  
	        }  
	          
	        if(mDataChanged){  
	            int oldCurrentX = mCurrentX;  
	            initView();  
	            removeAllViewsInLayout();  
	            mNextX = oldCurrentX;  
	            mDataChanged = false;  
	        }  
	  
	        if(mScroller.computeScrollOffset()){  
	            int scrollx = mScroller.getCurrX();  
	            mNextX = scrollx;  
	        }  
	          
	        if(mNextX <= 0){  
	            mNextX = 0;  
	            mScroller.forceFinished(true);  
	        }  
	        if(mNextX >= mMaxX) {  
	            mNextX = mMaxX;  
	            mScroller.forceFinished(true);  
	        }  
	          
	        int dx = mCurrentX - mNextX;  
	          
	        removeNonVisibleItems(dx);  
	        fillList(dx);  
	        positionItems(dx);  
	          
	        mCurrentX = mNextX;  
	          
	        if(!mScroller.isFinished()){  
	            post(new Runnable(){  
	                @Override  
	                public void run() {  
	                    requestLayout();  
	                }  
	            });  
	              
	        }  
	    }  
	      
	    private void fillList(final int dx) {  
	        int edge = 0;  
	        View child = getChildAt(getChildCount()-1);  
	        if(child != null) {  
	            edge = child.getRight();  
	        }  
	        fillListRight(edge, dx);  
	          
	        edge = 0;  
	        child = getChildAt(0);  
	        if(child != null) {  
	            edge = child.getLeft();  
	        }  
	        fillListLeft(edge, dx);  
	          
	          
	    }  
	      
	    private void fillListRight(int rightEdge, final int dx) {  
	        while(rightEdge + dx < getWidth() && mRightViewIndex < mAdapter.getCount()) {  
	              
	            View child = mAdapter.getView(mRightViewIndex, mRemovedViewQueue.poll(), this);  
	            addAndMeasureChild(child, -1);  
	            rightEdge += child.getMeasuredWidth();  
	              
	            if(mRightViewIndex == mAdapter.getCount()-1) {  
	                mMaxX = mCurrentX + rightEdge - getWidth();  
	            }  
	              
	            if (mMaxX < 0) {  
	                mMaxX = 0;  
	            }  
	            mRightViewIndex++;  
	        }  
	          
	    }  
	      
	    private void fillListLeft(int leftEdge, final int dx) {  
	        while(leftEdge + dx > 0 && mLeftViewIndex >= 0) {  
	            View child = mAdapter.getView(mLeftViewIndex, mRemovedViewQueue.poll(), this);  
	            addAndMeasureChild(child, 0);  
	            leftEdge -= child.getMeasuredWidth();  
	            mLeftViewIndex--;  
	            mDisplayOffset -= child.getMeasuredWidth();  
	        }  
	    }  
	      
	    private void removeNonVisibleItems(final int dx) {  
	        View child = getChildAt(0);  
	        while(child != null && child.getRight() + dx <= 0) {  
	            mDisplayOffset += child.getMeasuredWidth();  
	            mRemovedViewQueue.offer(child);  
	            removeViewInLayout(child);  
	            mLeftViewIndex++;  
	            child = getChildAt(0);  
	              
	        }  
	          
	        child = getChildAt(getChildCount()-1);  
	        while(child != null && child.getLeft() + dx >= getWidth()) {  
	            mRemovedViewQueue.offer(child);  
	            removeViewInLayout(child);  
	            mRightViewIndex--;  
	            child = getChildAt(getChildCount()-1);  
	        }  
	    }  
	      
	    private void positionItems(final int dx) {  
	        if(getChildCount() > 0){  
	            mDisplayOffset += dx;  
	            int left = mDisplayOffset;  
	            for(int i=0;i<getChildCount();i++){  
	                View child = getChildAt(i);  
	                int childWidth = child.getMeasuredWidth();  
	                child.layout(left, 0, left + childWidth, child.getMeasuredHeight());  
	                left += childWidth + child.getPaddingRight();  
	            }  
	        }  
	    }  
	      
	    public synchronized void scrollTo(int x) {  
	        mScroller.startScroll(mNextX, 0, x - mNextX, 0);  
	        requestLayout();  
	    }  
	      
	    @Override  
	    public boolean dispatchTouchEvent(MotionEvent ev) {  
	        boolean handled = super.dispatchTouchEvent(ev);  
	        handled |= mGesture.onTouchEvent(ev);  
	        return handled;  
	    }  
	      
	    protected boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX,  
	                float velocityY) {  
	        synchronized(HorizontalListView.this){  
	            mScroller.fling(mNextX, 0, (int)-velocityX, 0, 0, mMaxX, 0, 0);  
	        }  
	        requestLayout();  
	          
	        return true;  
	    }  
	      
	    protected boolean onDown(MotionEvent e) {  
	        mScroller.forceFinished(true);  
	        return true;  
	    }  
	      
	    private OnGestureListener mOnGesture = new GestureDetector.SimpleOnGestureListener() {  
	  
	        @Override  
	        public boolean onDown(MotionEvent e) {  
	            return HorizontalListView.this.onDown(e);  
	        }  
	  
	        @Override  
	        public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX,  
	                float velocityY) {  
	            return HorizontalListView.this.onFling(e1, e2, velocityX, velocityY);  
	        }  
	  
	        @Override  
	        public boolean onScroll(MotionEvent e1, MotionEvent e2,  
	                float distanceX, float distanceY) {  
	              
	            synchronized(HorizontalListView.this){  
	                mNextX += (int)distanceX;  
	            }  
	            requestLayout();  
	              
	            return true;  
	        }  
	  
	        @Override  
	        public boolean onSingleTapConfirmed(MotionEvent e) {  
	            for(int i=0;i<getChildCount();i++){  
	                View child = getChildAt(i);  
	                if (isEventWithinView(e, child)) {  
	                    if(mOnItemClicked != null){  
	                        mOnItemClicked.onItemClick(HorizontalListView.this, child, mLeftViewIndex + 1 + i, mAdapter.getItemId( mLeftViewIndex + 1 + i ));  
	                    }  
	                    if(mOnItemSelected != null){  
	                        mOnItemSelected.onItemSelected(HorizontalListView.this, child, mLeftViewIndex + 1 + i, mAdapter.getItemId( mLeftViewIndex + 1 + i ));  
	                    }  
	                    break;  
	                }  
	                  
	            }  
	            return true;  
	        }  
	          
	        @Override  
	        public void onLongPress(MotionEvent e) {  
	            int childCount = getChildCount();  
	            for (int i = 0; i < childCount; i++) {  
	                View child = getChildAt(i);  
	                if (isEventWithinView(e, child)) {  
	                    if (mOnItemLongClicked != null) {  
	                        mOnItemLongClicked.onItemLongClick(HorizontalListView.this, child, mLeftViewIndex + 1 + i, mAdapter.getItemId(mLeftViewIndex + 1 + i));  
	                    }  
	                    break;  
	                }  
	  
	            }  
	        }  
	  
	        private boolean isEventWithinView(MotionEvent e, View child) {  
	            Rect viewRect = new Rect();  
	            int[] childPosition = new int[2];  
	            child.getLocationOnScreen(childPosition);  
	            int left = childPosition[0];  
	            int right = left + child.getWidth();  
	            int top = childPosition[1];  
	            int bottom = top + child.getHeight();  
	            viewRect.set(left, top, right, bottom);  
	            return viewRect.contains((int) e.getRawX(), (int) e.getRawY());  
	        }  
	    };  
}
